A polymer composite for directional heat conduction and a preparation method and application thereof

Abstract

The application discloses a kind of polymer composite of directional heat conduction and preparation method and application thereof, belong to heat-conducting material technical field.The preparation method provided by the application adopts electrostatic spinning-3D printing integrated equipment;The equipment includes power supply with positive electrode and negative electrode;And negative electrode communication substrate;For the electrostatic spinning slurry is jetted to substrate and and positive electrode communication nozzle;Connecting nozzle and substrate, and drive its relative movement along preset trajectory movement module;In preparation process, electrostatic spinning slurry contains anisotropic heat-conducting filler;Electrostatic spinning slurry jetting speed is 1~3mL / h;Printing speed is 0.05~0.2m / s;Positive electrode and negative electrode pressure difference is-10~15kV.The preparation method provided by the application can effectively improve the thermal conductivity and structural precision of the obtained polymer composite.The application also provides the polymer composite of directional heat conduction prepared by the above preparation method and its application.

Description

Technical Field

[0001] This invention relates to the field of thermally conductive materials technology, and in particular to a directional thermally conductive polymer composite material, its preparation method, and its application. Background Technology

[0002] With the rapid development of microelectronics integration technology, the integration density of logic circuits is increasing rapidly, driving electronic devices towards thinner and smaller designs. This leads to a significant increase in the power density of electronic devices. During prolonged operation, this generates more heat, which can easily accumulate and cause internal temperatures to rise, severely impacting their stability and lifespan. Therefore, the market needs to provide thermal interface materials with high thermal conductivity.

[0003] Based on thermal orientation, thermal interface materials are divided into isotropic interface materials and anisotropic (directional thermal conduction) thermal interface materials. Compared with isotropic materials, anisotropic thermal interface materials can achieve higher thermal conductivity in a certain direction with less thermally conductive filler. Therefore, directional thermal conduction thermal interface materials are an important research direction in this field.

[0004] Traditional techniques primarily combine preparation methods with different types of thermally conductive fillers to achieve directional thermal conduction in thermal interface materials. Preparation methods can utilize shear forces during processing, external field assistance, filler arrays, and template methods to achieve the directional arrangement of thermally conductive fillers. While these methods can achieve directional thermal conduction to some extent, they either suffer from complex preparation methods, poor directional thermal conduction performance, or poor dimensional control. Therefore, there is an urgent need for a new preparation method that can obtain materials with directional thermal conduction through a simple approach. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a method for preparing a directional thermally conductive polymer composite material. When the amount of thermally conductive filler is constant, the thermal conductivity of the obtained polymer composite material can be effectively improved, and the structural accuracy of the obtained polymer composite material can be improved.

[0006] The present invention also provides a directional thermally conductive polymer composite material prepared by the above preparation method.

[0007] The present invention also provides applications of the above-described directional thermally conductive polymer composite material.

[0008] According to an embodiment of a first aspect of the present invention, a method for preparing a directional thermally conductive polymer composite material is provided, wherein the equipment used in the preparation method includes an electrospinning-3D printing integrated device; the electrospinning-3D printing integrated device includes:

[0009] A power source having a positive terminal and a negative terminal;

[0010] A substrate, wherein the substrate is connected to the negative electrode;

[0011] A nozzle for spraying electrospinning slurry toward the substrate, the nozzle being connected to the positive electrode;

[0012] A moving module, wherein the nozzle and / or the substrate are connected to the moving module, and the moving module drives the nozzle and the substrate to move relative to each other along a preset trajectory;

[0013] In the preparation process of the polymer composite material, the electrospinning slurry contains anisotropic thermally conductive fillers;

[0014] The spraying speed of the electrospinning slurry is 1-3 mL / h; the printing speed is 0.05-0.2 m / s; the voltage of the positive electrode is 5-15 kV; and the voltage of the negative electrode is -5 to -15 kV.

[0015] The preparation method according to embodiments of the present invention has at least the following beneficial effects:

[0016] The equipment used in the preparation method integrates 3D printing and electrospinning technologies, including a 3D printing mobile platform (mobile module), a high-voltage power supply for electrospinning, an electrospinning positive electrode injector (nozzle), and a programmable lattice-type negative electrode platform (substrate). By coordinating the control of the electrospinning integrated 3D printing equipment, the macroscopic structure of the polymer composite material can be designed.

[0017] The preparation method achieves the microscopic directional distribution of thermally conductive fillers inside the polymer composite material by controlling the spraying speed of the electrospinning slurry and the voltage of the positive and negative electrodes of the printing speed during the printing process, through precise control of the external electric field.

[0018] In summary, the preparation method provided by this invention, by adjusting specific equipment and parameters, can obtain polymer composite materials with designable macroscopic structures and microscopic directional thermal conductivity; thus broadening the research ideas for the preparation methods and applications of directional thermally conductive polymer composite materials.

[0019] According to some embodiments of the present invention, the 3D printing portion of the integrated device is fused deposition modeling (FDM) 3D printing.

[0020] According to some embodiments of the present invention, the preparation method further includes structural modeling and slicing before printing, generating a G-code file, and finally importing the G-code file into the electrospinning-3D printing integrated device. The structural modeling involves designing a specific macroscopic structure, and the slicing aims to convert the macroscopic structure into a language recognizable by the electrospinning-3D printing integrated device, i.e., a G-code file. The slicing can also promote the formation of a microscopic directional distribution of the thermally conductive filler (mainly controlling the thickness of the slices). Thus, in the resulting polymer composite material, the microscopic thermally conductive filler is directionally distributed, the macroscopic structure can be designed, and the performance is superior.

[0021] According to some embodiments of the present invention, the software for structural modeling includes at least one of Solidworks, UG, and Pro / E. The shape of the structural modeling design includes at least one of coin-shaped, square plate-shaped, circular plate-shaped, and irregular plate-shaped.

[0022] According to some embodiments of the present invention, the software for slicing includes at least one of Slicer and Cura.

[0023] The G-code file includes the orientation data of the nozzle and the substrate. This allows for better precision control of both macroscopic and microscopic structures.

[0024] According to some embodiments of the present invention, the substrate is a dot-matrix negative electrode with programmable motion data. Combined with the parameters of the preparation method, the programmability of the substrate can further improve the directional distribution (higher precision) of the thermally conductive filler in the polymer composite material, thereby obtaining a polymer composite material with higher directional thermal conductivity.

[0025] According to some embodiments of the present invention, the nozzle is a syringe, specifically a positive electrode injection component for electrospinning.

[0026] According to some embodiments of the present invention, the electrospinning-3D printing integrated equipment further includes a support frame. The movable module is movably fixed to the support frame. Thus, the support frame serves to provide support and initial positioning.

[0027] According to some embodiments of the present invention, the thermally conductive filler is made of at least one of inorganic non-metals, metals, and metal oxides.

[0028] According to some embodiments of the present invention, the microstructure of the thermally conductive filler includes at least one of sheet-like, tubular, and fibrous shapes.

[0029] According to some embodiments of the present invention, the thermally conductive filler includes at least one of boron nitride nanosheets, graphite microsheets, carbon nanotubes, nanocellulose and carbon fibers.

[0030] According to some embodiments of the present invention, the thermally conductive filler is selected from boron nitride nanosheets. The average diameter of the boron nitride nanosheets is between 100 and 150 nm, specifically about 120 nm. The average thickness of the boron nitride nanosheets is 15 to 25 nm, specifically about 20 nm.

[0031] According to some embodiments of the present invention, the thermally conductive filler is selected from graphite flakes (GNP) and cellulose nanoparticles (CNC). The mass ratio of the graphite flakes to the cellulose nanoparticles is 1.5–2.5:1, specifically about 2:1. The thickness of the graphite flakes is 0.5–1.5 nm. The diameter of the graphite flakes is 0.1–5 μm, specifically about 0.5 μm or about 3 μm. The diameter of the cellulose nanoparticles is 90–110 nm, specifically about 100 nm. The aspect ratio of the cellulose nanoparticles is 250–350, specifically about 300.

[0032] According to some embodiments of the present invention, the thermally conductive filler is selected from carbon nanotubes (CNTs) and carbon fibers (SCFs). The mass ratio of the carbon nanotubes to carbon fibers is 1:1.5 to 2.5, specifically about 1:2. The diameter of the carbon nanotubes is 20 to 100 nm, specifically about 30 nm or about 70 nm. The length of the carbon nanotubes is ≥2 μm. The average diameter of the carbon fibers is 8 to 12 μm, specifically about 10 μm. The average density of the carbon fibers is 2 to 2.5 g / cm³. 3 For example, it could be approximately 2.20 g / cm³. 3 .

[0033] According to some embodiments of the present invention, the raw materials for preparing the electrospinning slurry also include polymers.

[0034] According to some embodiments of the present invention, the polymer includes at least one selected from polyurethane, polyamide, polyacrylonitrile, polyvinyl alcohol, and polylactic acid.

[0035] According to some embodiments of the present invention, the mass ratio of the thermally conductive filler to the polymer is 3:2 to 15. For example, it can be about 1:1, 3:4, 3:5 or about 3:10.

[0036] According to some embodiments of the present invention, the raw materials for preparing the electrospinning slurry also include a solvent.

[0037] According to some embodiments of the present invention, the solvent includes at least one of acetone, ethanol and dimethyl methacrylate.

[0038] According to some embodiments of the present invention, the mass ratio of the thermally conductive filler to the volume ratio of the solvent is 1g:10-60mL. For example, it can be approximately 1g:30mL, 1g:40mL, 1g:45mL, 1g:48mL, or approximately 1g:50mL.

[0039] According to some embodiments of the present invention, the thermally conductive filler is modified before the electrospinning slurry is prepared.

[0040] According to some embodiments of the present invention, the modification method includes at least one of physical, chemical, and mechanochemical methods. The aim is to improve the bonding ability between the polymer and the thermally conductive filler during the printing process. A second aim of the modification is to enhance the functional properties of the polymer composite material and expand its application range.

[0041] The modification method according to some embodiments of the present invention includes treating the thermally conductive filler with a coupling agent. Specifically, the treatment method includes co-dispersing the coupling agent and the thermally conductive filler in an alcohol solvent, followed by solid-liquid separation, washing with water, and drying. The mass ratio of the coupling agent to the thermally conductive filler is 1:45 to 55, for example, about 1:50. The coupling agent includes a silane coupling agent. After dispersion in the alcohol solvent, the resulting pH is 4 to 5. The dispersion time is 25 to 35 minutes, for example, about 30 minutes. The mass-to-volume ratio of the thermally conductive filler to the alcohol solvent is 1 g: 15 to 25 mL, for example, about 1 g: 20 mL.

[0042] According to some embodiments of the present invention, the raw materials for preparing the electrospinning slurry further include a dispersant. This can improve the dispersion stability of the electrospinning slurry.

[0043] According to some embodiments of the present invention, the dispersant comprises sodium dodecyl sulfate.

[0044] According to some embodiments of the present invention, the mass concentration of the dispersant in the electrospinning slurry is between 0.1% and 2%. Specifically, it may be about 0.5%, 1.0%, or about 1.55%.

[0045] According to some embodiments of the present invention, the method for preparing the electrospinning slurry includes mixing the polymer, thermally conductive filler and solvent.

[0046] The mixing method includes at least one of stirring and sonication.

[0047] The mixing method is simple stirring.

[0048] The mixing method involves sequential stirring and sonication.

[0049] The stirring speed is 500–1500 r / s; specifically, it can be about 1000 r / s, 1200 r / s, or about 1300 r / s. The stirring duration is 0.5–2.5 h; specifically, it can be about 1 h, 1.5 h, or about 2 h.

[0050] The duration of the ultrasound is 10 to 60 minutes; for example, it can be about 20 minutes, 30 minutes or about 40 minutes.

[0051] The raw materials and concentrations of each component in the preparation of the electrospinning slurry can be adjusted according to the actual application of the resulting polymer composite material. In the preparation method, the electrospinning slurry is filled into the nozzle and sprayed onto the substrate by the nozzle.

[0052] According to some embodiments of the present invention, the printing speed is 0.08 to 0.15 m / s. Specifically, it can be about 0.1 m / s. The printing speed is the linear velocity of the relative movement of the printhead and the substrate.

[0053] According to some embodiments of the present invention, the spraying rate of the electrospinning slurry is 1.5 to 2.5 mL / h. For example, it can be about 2 mL / h.

[0054] According to some embodiments of the present invention, the voltage range of the positive electrode is 8 to 12 kV. For example, it can be approximately 10 kV.

[0055] According to some embodiments of the present invention, the voltage range of the negative electrode is -10 to 0 kV. For example, it can be approximately -5 kV.

[0056] According to an embodiment of the second aspect of the present invention, a directional thermally conductive polymer composite material prepared by the preparation method described above is provided; the thermal conductivity of the polymer composite material is ≥3 W / m·K.

[0057] Since the directional thermally conductive polymer composite material adopts all the technical solutions of the preparation method of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments.

[0058] According to some embodiments of the present invention, the thermal conductivity of the polymer composite material is ≥5 W / m·K. Specifically, it can be about 6 W / m·K, 8 W / m·K, 10 W / m·K, or about 12 W / m·K.

[0059] According to some embodiments of the present invention, the polymer composite material possesses at least one of the following properties:

[0060] (1) Thermally conductive and insulating;

[0061] (2) Thermally conductive electromagnetic shielding;

[0062] (3) Thermal and electrical conductivity.

[0063] Wherein, when the polymer composite material has thermal and electromagnetic shielding, it has at least one of the following parameters:

[0064] (1)SE A ≥25dB;

[0065] (2)SE R ≥10dB;

[0066] (3)SE T ≥38dB.

[0067] When the polymer composite material possesses thermal and electrical conductivity, its electrical conductivity is ≥35 S / m. For example, it can be approximately 40 S / m.

[0068] According to some embodiments of the present invention, the mechanical strength of the polymer composite material is ≥12 MPa. For example, it can be about 30 MPa, 40 MPa, 50 MPa, 60 MPa or about 70 MPa.

[0069] According to some embodiments of the present invention, in the polymer composite material, the thermally conductive filler is uniaxially oriented and ordered.

[0070] According to an embodiment of a third aspect of the present invention, the application of the polymer composite material described herein is provided in thermal management of electronic devices, automotive cooling systems, and the energy industry.

[0071] Since the application adopts all the technical solutions of the polymer composite materials of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments.

[0072] Unless otherwise specified, the term "about" in this invention actually means that the error is allowed to be within ±2%, for example, about 100 is actually 100 ± 2% × 100.

[0073] Unless otherwise specified, "between" in this invention includes the number itself, for example, "between 2 and 3" includes the endpoint values ​​2 and 3.

[0074] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0075] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0076] Figure 1 This is a schematic diagram of the electrospinning-3D printing integrated equipment used in Embodiment 1 of the present invention.

[0077] Figure 2 yes Figure 1 Enlarged schematic diagram of the middle substrate and schematic diagram of the printing direction.

[0078] Figure 3 This is the structural model of the directional thermally conductive polymer composite material obtained in Example 1 of the present invention.

[0079] Figure 4 This is the structural model of the directional thermally conductive polymer composite material obtained in Example 2 of the present invention.

[0080] Figure 5 This is the structural model of the directional thermally conductive polymer composite material obtained in Example 3 of the present invention.

[0081] Figure label:

[0082] Power supply 100, nozzle 200, moving module 300, substrate 400, bracket 500, dot matrix 600. Detailed Implementation

[0083] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0084] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0085] Example 1

[0086] This example demonstrates the fabrication of a directional thermally conductive polymer composite material. A schematic diagram of the structure using an electrospinning-3D printing integrated equipment is shown below. Figures 1-2 As shown, the device includes the following components:

[0087] Power supply 100, which has a positive terminal and a negative terminal;

[0088] Substrate 400 is connected to the negative electrode;

[0089] Nozzle 200 is used to spray electrospinning slurry toward substrate 400. Nozzle 200 is connected to the positive electrode. Nozzle 200 is actually a graduated syringe (maximum graduation 20mL) containing electrospinning slurry.

[0090] The moving module 300, the nozzle 200 and the substrate 400 are connected to the moving module 300, and the moving module 300 drives the nozzle 200 and the substrate 400 to move relative to each other along a preset trajectory.

[0091] Bracket 500 is used to fix and support the moving module 300.

[0092] It is understandable that, upon magnifying the substrate 400, a dot matrix 600 can be seen on the substrate 400. Therefore, in actual production, the relative movement path between the substrate 400 and the nozzle 200 can be designed by programming the dot matrix 600 (e.g., ...). Figure 2 (As shown).

[0093] The preparation method provided in this example includes the following steps:

[0094] S1. Preparation Phase:

[0095] Programming: First, model using Solidworks, such as... Figure 3 The model shown is then imported into 3D printing slicing software to generate a G-code data file that can be recognized by the electrospinning-3D printing integrated device.

[0096] Preparation of electrospinning slurry: Add 10g of PLA (polylactic acid, NatureWorks, USA, grade: 4032D) to 90mL of acetone solution and stir to dissolve. Then add 2g of BNNs (boron nitride nanosheets, Aladdin, USA, with an average diameter of 120 nm and a thickness of 20 nm) thermally conductive filler and stir continuously at 1000r / s for 1h to obtain electrospinning slurry.

[0097] S2. Preparation stage: The electrospinning slurry obtained in step S1 is filled into the syringe of nozzle 200. The printing speed is set to 0.2m / s, the electrospinning slurry extrusion rate is 2mL / h, and the positive and negative electrode voltages are -5kV and 10kV, respectively. Then, according to the G-code data converted from the model, the electrospinning-3D printing integrated equipment is driven to operate to obtain a directional thermally conductive polymer composite material (referred to as BNNs / PLA).

[0098] Example 2

[0099] This example prepares a directional thermally conductive polymer composite material, which differs from Example 1 in that:

[0100] (1) In step S1, the established model is as follows: Figure 4 As shown, the resulting polymer composite material is abbreviated as GNP / CNC / PVA.

[0101] (2) In step S1, the preparation steps of electrospinning slurry are as follows: GNP (nanographite sheets, Shanghai Pantian Powder Materials Co., Ltd., with a thickness of 0.55-1.2nm and a diameter of 0.5-3μm) is modified by adding GNP (10g) and silane coupling agent (0.2g) in a mass ratio of 50:1 to 200mL of ethanol solvent, and adding an appropriate amount of hydrochloric acid to control the pH value of the solution at about 4-5. Then, ultrasonic dispersion is performed for 30min, and continuous stirring is performed at 1000r / s for 1h. After washing with water and drying, the modified GNP filler is obtained. Add 2g of modified GNP, 1g of CNC (nanocellulose, Jinan Shengquan Group Co., Ltd., CNC with a diameter of 100nm and an aspect ratio of 300) and 2g of PVA (polyvinyl alcohol (type 1788, Aladdin Company, USA, degree of alcoholysis: 87.0-89.0% (mol / mol)) to 100mL of ethanol, then add 1g of SDS dispersant (sodium dodecyl sulfate, Aladdin Company, USA, purity ≥90%). Stir continuously at 1200r / s for 2h, then continue to disperse by ultrasonication for 30min to obtain electrospinning slurry.

[0102] (3) In step S2, the printing speed is set to 0.15m / s, the electrospinning slurry extrusion speed is 1.5mL / h, and the positive and negative electrode voltages are -5kV and 15kV, respectively.

[0103] (4) The syringe has a capacity of 10 mL.

[0104] Example 3

[0105] This example prepares a directional thermally conductive polymer composite material, which differs from Example 1 in that:

[0106] (1) In step S1, the established model is as follows: Figure 5 As shown, the resulting polymer composite material is abbreviated as CNT / SCF / PAN.

[0107] (2) In step S1, the preparation of the electrospinning slurry is as follows: 5g of PAN (polyacrylonitrile) is added to 100mL of dimethylformamide solvent, stirred thoroughly and dissolved to obtain a PAN solution; then, 1g of CNT (carbon nanotubes, Russian Nano-Tech Center Co., Ltd., with a diameter of 30-70nm and a length greater than 2μm) and 2g of SCF (short-cut carbon fiber, Shanghai Lishuo Composite Materials Co., Ltd., with a diameter of 10μm and an average density of 2.20g / cm³) and 2g of SCF (short-cut carbon fiber, Shanghai Lishuo Composite Materials Co., Ltd., with a diameter of 10μm and an average density of 2.20g / cm³) are added to the PAN solution. 3 Add 1g SDS (sodium dodecyl sulfate) as a dispersant, and stir the mixed solution at 1000r / s for 1h to obtain electrospinning slurry;

[0108] (3) In step S2, the printing speed is set to 0.2 m / s. The electrospinning slurry extrusion rate is 1.8 mL / h.

[0109] Comparative Example 1: This example prepared a polymer composite material, which differs from Example 1 in that:

[0110] (1) In step S2, BNNs / PLA thermally conductive composite material (including a positive electrostatic injection device and a negative roller receiver) is prepared using conventional electrospinning equipment without synchronously directional movement of the positive and negative electrodes. The roller rotation speed is set to 200 r / min (linear speed is approximately 0.2 m / s); the negative electrode voltage of the roller is -5 kV, the positive electrode injector voltage is 10 kV, and the extrusion speed is 2 mL / h.

[0111] Comparative Example 2

[0112] This example prepares a polymer composite material, which differs from Example 2 in that:

[0113] (1) In step S2, the GNP / CNC / PVA thermally conductive and electromagnetically shielded composite material (including a positive electrostatic injection device and a negative roller receiver) is prepared by conventional electrospinning without synchronously directional movement of the positive and negative electrodes. The roller speed is set to 200 r / min (linear speed is approximately 0.2 m / s); the negative electrode voltage of the roller is -5 kV, the positive electrode injector voltage is 15 kV, and the extrusion speed is 1.8 mL / h.

[0114] Comparative Example 3

[0115] This example prepares a polymer composite material, which differs from Example 3 in that:

[0116] (1) In step S2, CNT / SCF / PAN thermally conductive composite materials (including a positive electrostatic injection device and a negative roller receiver) are prepared by conventional electrospinning without synchronously directional movement of the positive and negative electrodes. The roller rotation speed is set to 150 r / min (linear speed is approximately 0.15 m / s); the negative electrode voltage of the roller is -5 kV, the positive electrode injector voltage is 15 kV, and the extrusion speed is 1.5 mL / h.

[0117] Comparative Example 4

[0118] This example prepares a polymer composite material, which differs from Example 1 in that:

[0119] (1) In step S2, the printing speed is set to 0.5 m / s, the electrospinning slurry extrusion rate is 0.5 mL / h, and the positive and negative electrode voltages are 0 kV and 15 kV, respectively.

[0120] The polymer composite material obtained in this example has a discontinuous internal network with broken filaments, making it impossible to construct a continuous thermally conductive network.

[0121] From a macroscopic perspective, the shape of the polymer composite material obtained in this example is similar to that of Example 1. However, the thermal conductivity and mechanical properties of the obtained polymer composite material sample are reduced, with a thermal conductivity of only 1.3 W / m·K and a mechanical strength of 28 MPa.

[0122] Test case

[0123] This example tested the thermally conductive filler's orientation, in-plane thermal conductivity, and mechanical strength in the polymer composites obtained in the examples and comparative examples. The specific testing methods were as follows: Orderliness was tested using SEM to determine if the alignment of the printed direction was parallel; thermal conductivity was tested using a Netzsch LFA457 instrument (Germany); mechanical strength was tested using a ZQ-990-2 tensile testing machine (tensile strength) from Dongguan Zhiqu Precision Co., Ltd.; electromagnetic shielding was tested using a Keysight Technologies N5224B PNA vector network analyzer (China). Electrical conductivity was tested and calculated using a digital bridge (VICTOR 4090C). The test results are shown in Table 1.

[0124] Table 1. Properties of the polymer composite materials obtained in the examples and comparative examples.

[0125]

[0126] In Table 1, uniaxial orientation order refers to the conductive filler being arranged horizontally in one direction on the substrate, for example, specifically along... Figure 2 The paths shown are oriented.

[0127] Comparing Examples 1-3, it can be seen that the mechanical strength of the obtained polymer composite material is mainly related to the type of polymer used, and the additional properties such as electrical conductivity and thermal conductivity of the obtained polymer composite material are mainly related to the performance of the conductive filler therein. However, by using specific equipment and setting specific parameters, the present invention can obtain a polymer composite material with directional thermal conductivity and adjustable micro and macro structures.

[0128] Comparing Examples 1-3 with Comparative Examples 1-3, it is evident that the macroscopic structure of the polymer composite material obtained using conventional equipment and methods is difficult to control, and a directional heat-conducting network cannot be obtained in the plane. The overall performance of the materials obtained in the comparative examples is significantly lower than that of the corresponding examples.

[0129] Comparing Example 1 and Comparative Example 4, it can be seen that if the equipment provided by the present invention is used, but the parameters are not within the range provided by the present invention, the in-plane order of the thermally conductive filler and the overall performance of the resulting polymer composite material will also be affected.

[0130] Based on the above results, it can be seen that the preparation method provided by the present invention, through the synergistic effect between the equipment used and the designed parameters, can prepare a directional thermally conductive polymer composite material with ordered macroscopic structure and microscopic thermally conductive filler arrangement, and the obtained polymer composite material can meet the requirements of high thermal conductivity.

[0131] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A method for preparing a directional thermally conductive polymer composite material, characterized in that, The equipment used in the preparation method includes an integrated electrospinning-3D printing device; the integrated electrospinning-3D printing device includes: A power source having a positive terminal and a negative terminal; A substrate, wherein the substrate is connected to the negative electrode; A nozzle for spraying electrospinning slurry toward the substrate, the nozzle being connected to the positive electrode; A moving module, wherein the nozzle and / or the substrate are connected to the moving module, and the moving module drives the nozzle and the substrate to move relative to each other along a preset trajectory; In the preparation process of the polymer composite material, the electrospinning slurry contains anisotropic thermally conductive fillers; The spraying speed of the electrospinning slurry is 1~3 mL / h; the printing speed is 0.05~0.2 m / s; the voltage of the positive electrode is 5~15 kV; and the voltage of the negative electrode is -5~-15 kV.

2. The preparation method according to claim 1, characterized in that, The thermally conductive filler material includes at least one of inorganic non-metals, metals, and metal oxides.

3. The preparation method according to claim 1, characterized in that, The thermally conductive filler includes at least one of boron nitride nanosheets, graphite microsheets, carbon nanotubes, nanocellulose, and carbon fibers.

4. The preparation method according to claim 1, characterized in that, The raw materials for preparing the electrospinning slurry also include polymers.

5. The preparation method according to claim 4, characterized in that, The polymer includes at least one of polyurethane, polyamide, polyacrylonitrile, polyvinyl alcohol, and polylactic acid.

6. The preparation method according to claim 4, characterized in that, The mass ratio of the thermally conductive filler to the polymer is 3:2~15.

7. The preparation method according to any one of claims 1 to 6, characterized in that, The raw materials for preparing the electrospinning slurry also include solvents.

8. The preparation method according to claim 7, characterized in that, The solvent includes at least one of acetone, ethanol, and dimethylformamide.

9. The preparation method according to claim 7, characterized in that, The mass ratio of the thermally conductive filler to the volume ratio of the solvent is 1g:10~60mL.

10. The preparation method according to any one of claims 1 to 6, characterized in that, The substrate is a dot-matrix negative electrode with programmable motion data.

11. A directional thermally conductive polymer composite material prepared by the preparation method according to any one of claims 1 to 10; characterized in that, The thermal conductivity of the polymer composite material is ≥3W / m·K.

12. The application of the polymer composite material as described in claim 11 in thermal management of electronic devices, automotive cooling systems, and the energy industry.

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